Convetionally, a pressure regulating valve is provided in a supply system that supplies fluid, which is gaseous fuel for example, to an internal combustion engine. The pressure regulating valve storage reduces the pressure of the gaseous fuel from a high tank pressure to a specified pressure and supplies the gaseous fuel with the reduced pressure to a fuel injection valve, as described in Japanese Laid-Open Patent Publication No. 2012-73886.
The pressure regulating valve disclosed in Japanese Laid-Open Patent Publication No. 2012-73886 includes a valve chamber in communication with an inflow portion, into which the gaseous fuel flows, and a pressure regulation chamber in communication with an outflow portion, which discharges the gaseous fuel. The pressure regulating valve includes a valve seat member, which separates the valve chamber and the pressure regulation chamber from each other. The pressure regulating valve further includes a valve arranged in the valve chamber and an urging member. The valve relatively moves toward or away from the valve seat member. The urging member applies an urging force to the valve in a direction toward the valve seat member. The valve includes a protrusion, which protrudes to the pressure regulation chamber through an opening formed in the valve seat member.
The pressure regulating valve includes a piston formed from magnetic material and an electromagnetic actuator. The piston separates the pressure regulation chamber and a back pressure chamber from each other. The electromagnetic actuator drives the piston to move in the direction toward or away from the valve seat member. The piston contacts the tip end of the protrusion of the valve. The force by which the piston pushes the valve is adjusted according to the driving state of the actuator.
Specifically, when the amount of injection of fuel through the fuel injection valve is small and the set pressure in a delivery pipe, which temporarily stores gaseous fuel to be supplied to the injection valve, is set comparatively low during the idling operation, for example, current is not supplied to the actuator. This reduces the force by which the piston pushes the valve, so that the opening degree of the opening in the valve seat member is unlikely to be increased. In contrast, when the amount of injection of fuel through the fuel injection valve is great and the set pressure in the delivery pipe is set comparatively high, current is supplied to the actuator. This increases the force by which the piston pushes the valve, so that the opening degree of the opening in the valve seat member is likely to be increased.
In the case of the above pressure regulating valve, the valve is moved in the direction away from the valve seat member against the urging froce by the urging member to increase the opening degree of the opening in the valve seat member. Accordingly, the urging force by the urging member is reduced so that the valve is easily moved in the direction away from the valve seat member. In this case, when a large amount of gaseous fuel needs to flow from the valve chamber into the pressure regulation chamber such as when the set pressure is high or when the fluid pressure in the storage tank is low and the fluid pressure in the valve chamber is low, the opening degree of the opening is likely to be increased. In this case, the fluid pressure in the pressure regulation chamber, i.e., the fluid pressure downstream from the pressure regulating valve is regulated with high accuracy.
In contrast, when the flow rate of gaseous fuel from the valve chamber into the pressure regulation chamber needs to be reduced such as when the set pressure is low or when the fluid pressure in the storage tank is high and the fluid pressure in the valve chamber is high, fine adjustment of the opening degree of the opening is hard to be performed. This leads to reduction of the regulation performance of the fluid pressure in the pressure regulation chamber.
On the other hand, if the urging force by the urging member is increased, the fine adjustment of the opening degree of the opening is easily performed. Accordingly, when the flow rate of gaseous fuel from the valve chamber into the pressure regulation chamber needs to be reduced as described above, the fluid pressure in the pressure regulation chamber is regulated with high accuracy. In contrast, when a large amount of the gaseous fuel needs to flow from the valve chamber into the pressure regulation chamber as described above, the opening degree of the opening is unlikely to be increased. In this case, this leads to reduction of the regulation performance of the fluid pressure in the pressure regulation chamber.